The proposed Clinical Assessment Core represents an evolution of methods from our past nine years of studies and will continue to carry out essential aspects of participant follow-up, assessment, and diagnosis for the projects. In our follow-up of the WHICAP II cohort, we will maintain uniformity and coherence in our approach to case identification. Guided by a tracking form generated by the Epidemiology, Database Management and Statistics Core, participants are contacted, interviewed and examined in a standardized fashion every 12-18 months. All subjects are administered measures assessing personal self-maintenance activities, perceived difficulty with memory, and mobility. Comprehensive neuropsychological testing includes measures of memory, language, executive functioning, visuospatial skill, and orientation. Neuropsychological data are available to the projects through raw and demographically corrected individual tests scores, and Neuropsychological Factor Scores representing memory, executive function, and language abilities. All participants receive a medical/psychiatric evaluation and an assessment of functional capacity that is independent of neuropsychological test performance. Participants with history of stroke or Parkinson's disease or those with functional or neuropsychoiogical signs of dementia will receive an evaluation by a board-certified neurologist. Information for all participants is reviewed at a diagnostic consensus conference of neuropsychologists, research physicians, and neurologists, and diagnoses are derived based on standardized diagnostic criteria. Emphasis has been placed on the consistency of these criteria over the entire study period. The clinical core will coordinate with the Brain Imaging Core to schedule eligible participants for MRI scans. The Clinical Assessment Core also coordinates with the Pathology Molecular Core to approach all participants about brain donation, obtain provisional consent, and obtain autopsies at the time of death.